### Dr. Sudoku Prescribes #54 – Deficit/Surplus Sudoku

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: L’s Big and Small

Rules: Combined Deficit and Surplus Sudoku rules, with some regions with fewer numbers (no repeats but one number missing) and others with more numbers (1-8 plus one repeat) than expected in a Sudoku. Use numbers from 1-8.

Answer String: Enter the 4th row from left to right, followed by a comma, followed by the 8th row from left to right.

Time Standards (highlight to view): Grandmaster = 4:30, Master = 7:00, Expert = 14:00

Solution: PDF

• Tom Collyer says:

The time standards here seem fairly generous – I’d have thought thought a world beating time was about half the quoted GM time. I suppose the big thing with this type is how comfortable with the geometry you are…

The answer keys were spot on! 🙂

• drsudoku says:

I’m inclined to agree with you, but will note this variant affects different solvers greatly. This was the first week I failed to predict my testers results right, even after significantly rewriting some of the puzzles. Having to choose between my own timing and my testers, I’ll have to side with my testers.

• Para says:

I know for me personally Sudokus that combines multiple variants, even if they’re this related, I always mess up a bit more and slow down because of it. I either forget to use a rule, or like in this case constantly mess up when switching between regions.

• TheSubro says:

Tom –

I think these are when you are at your best. Where other designers’ variant puzzles tend to fall back to choppy solves, yours are usually very fluid.

Reminds me a bit of the great flow of some of your earliest Art of Puzzles constructions.

Loved the ways that you played with the geometry and crossing numbers. I rarely keep my sudoku variant scores within Expert level, but found my way here easily.

Pleasant Saturday afternoon diversion. Thanks.

TheSubro

• Scott Handelman says:

Ah, damn you Snyder. This was the first puzzle of yours that I broke and didn’t notice until I tried to enter the (incorrect) solution. I made a gigantic incorrect assumption…and this is obviously a huge spoiler…that the four missing digits were different.

• Another nice smooth solve. Not too hard, not too easy, juuuuuusssst right. And now I’m off to take a nap in the medium sized bed.

• skynet says:

10:32 s
It was quite some time before things began to fall in place and the grey cells in the brain began to understand what was going on in the sudoku.
Once the input was fed correctly into the brain( that the 7 cell region will have one number short in the 1-8 range and the 9 cell region would have 1 number extra in 1-8 range)
Nice sudoku and the starting points of the solve are beautifully placed!!!

• Tricia says:

It took me three times to solve this correctly, not because I didn’t see the necessary logical steps, but because I apparently cannot count to 8. I need to get better at spotting the missing number or numbers in a row or column quickly. When I try to work fast, I invariably write down an incorrect number at some point. This seems to be my Sudoku weakness.

I think I’d have solved it in about 5 minutes if it weren’t for the silly errors. But then, trying to get a good time is probably what caused the errors in the first place.

• Carl W says:

I don’t want to know how many times I broke this puzzle. I kept thinking it was because I botched deficit regions, (oh, look there’s only one place a 3 could go in this region!), which I’m sure I did several times.

But what I didn’t realize is that, like Scott, I kept thinking the missing/extra digits were all unique.

So I really fell into that trap. Well done, Thomas!

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